[NOD-641] Upgrade to github.com/pkg/errors v0.9.1 and use errors.As where needed (#614)

* [NOD-641] Upgrade to github.com/pkg/errors v0.9.1 and use errors.As where needed

* [NOD-641] Fix find and replace error

* [NOD-641] Use errors.As for error type checking

* [NOD-641] Fix errors.As for pointer types

* [NOD-641] Use errors.As where needed

* [NOD-641] Rename rErr->ruleErr

* [NOD-641] Rename derr->dbErr

* [NOD-641] e->flagsErr where necessary

* [NOD-641] change jerr to more appropriate name

* [NOD-641] Rename cerr->bdRuleErr

* [NOD-641] Rename serr->scriptErr

* [NOD-641] Use errors.Is instead of testutil.AreErrorsEqual in TestNewHashFromStr

* [NOD-641] Rename bdRuleErr->dagRuleErr

* [NOD-641] Rename mErr->msgErr

* [NOD-641] Rename dErr->deserializeErr

blockdag/accept.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"github.com/kaspanet/kaspad/database"
 	"github.com/kaspanet/kaspad/util"
+	"github.com/pkg/errors"
 )
 
 func (dag *BlockDAG) addNodeToIndexWithInvalidAncestor(block *util.Block) error {
@@ -30,7 +31,8 @@ func (dag *BlockDAG) addNodeToIndexWithInvalidAncestor(block *util.Block) error
 func (dag *BlockDAG) maybeAcceptBlock(block *util.Block, flags BehaviorFlags) error {
 	parents, err := lookupParentNodes(block, dag)
 	if err != nil {
-		if rErr, ok := err.(RuleError); ok && rErr.ErrorCode == ErrInvalidAncestorBlock {
+		var ruleErr RuleError
+		if ok := errors.As(err, &ruleErr); ok && ruleErr.ErrorCode == ErrInvalidAncestorBlock {
 			err := dag.addNodeToIndexWithInvalidAncestor(block)
 			if err != nil {
 				return err

blockdag/accept_test.go

@@ -1,6 +1,7 @@
 package blockdag
 
 import (
+	"errors"
 	"path/filepath"
 	"testing"
 
@@ -33,8 +34,8 @@ func TestMaybeAcceptBlockErrors(t *testing.T) {
 		t.Errorf("TestMaybeAcceptBlockErrors: rejecting the block if its parents are missing: "+
 			"Expected: %s, got: <nil>", ErrParentBlockUnknown)
 	}
-	ruleErr, ok := err.(RuleError)
+	var ruleErr RuleError
-	if !ok {
+	if ok := errors.As(err, &ruleErr); !ok {
 		t.Errorf("TestMaybeAcceptBlockErrors: rejecting the block if its parents are missing: "+
 			"Expected RuleError but got %s", err)
 	} else if ruleErr.ErrorCode != ErrParentBlockUnknown {
@@ -71,8 +72,7 @@ func TestMaybeAcceptBlockErrors(t *testing.T) {
 		t.Errorf("TestMaybeAcceptBlockErrors: rejecting the block if its parents are invalid: "+
 			"Expected: %s, got: <nil>", ErrInvalidAncestorBlock)
 	}
-	ruleErr, ok = err.(RuleError)
+	if ok := errors.As(err, &ruleErr); !ok {
-	if !ok {
 		t.Errorf("TestMaybeAcceptBlockErrors: rejecting the block if its parents are invalid: "+
 			"Expected RuleError but got %s", err)
 	} else if ruleErr.ErrorCode != ErrInvalidAncestorBlock {
@@ -91,8 +91,7 @@ func TestMaybeAcceptBlockErrors(t *testing.T) {
 		t.Errorf("TestMaybeAcceptBlockErrors: rejecting the block due to bad context: "+
 			"Expected: %s, got: <nil>", ErrUnexpectedDifficulty)
 	}
-	ruleErr, ok = err.(RuleError)
+	if ok := errors.As(err, &ruleErr); !ok {
-	if !ok {
 		t.Errorf("TestMaybeAcceptBlockErrors: rejecting the block due to bad context: "+
 			"Expected RuleError but got %s", err)
 	} else if ruleErr.ErrorCode != ErrUnexpectedDifficulty {

blockdag/dag.go

@@ -484,7 +484,7 @@ func (dag *BlockDAG) addBlock(node *blockNode,
 	// Connect the block to the DAG.
 	chainUpdates, err := dag.connectBlock(node, block, selectedParentAnticone, fastAdd)
 	if err != nil {
-		if _, ok := err.(RuleError); ok {
+		if errors.As(err, &RuleError{}) {
 			dag.index.SetStatusFlags(node, statusValidateFailed)
 		} else {
 			return nil, err
@@ -574,8 +574,9 @@ func (dag *BlockDAG) connectBlock(node *blockNode,
 	newBlockUTXO, txsAcceptanceData, newBlockFeeData, err := node.verifyAndBuildUTXO(dag, block.Transactions(), fastAdd)
 	if err != nil {
 		newErrString := fmt.Sprintf("error verifying UTXO for %s: %s", node, err)
-		if err, ok := err.(RuleError); ok {
+		var ruleErr RuleError
-			return nil, ruleError(err.ErrorCode, newErrString)
+		if ok := errors.As(err, &ruleErr); ok {
+			return nil, ruleError(ruleErr.ErrorCode, newErrString)
 		}
 		return nil, errors.New(newErrString)
 	}
@@ -1832,7 +1833,7 @@ func (dag *BlockDAG) processDelayedBlocks() error {
 			log.Errorf("Error while processing delayed block (block %s)", delayedBlock.block.Hash().String())
 			// Rule errors should not be propagated as they refer only to the delayed block,
 			// while this function runs in the context of another block
-			if _, ok := err.(RuleError); !ok {
+			if !errors.As(err, &RuleError{}) {
 				return err
 			}
 		}

blockdag/dag_test.go

@@ -6,6 +6,7 @@ package blockdag
 
 import (
 	"fmt"
+	"github.com/pkg/errors"
 	"os"
 	"path/filepath"
 	"testing"
@@ -164,12 +165,13 @@ func TestIsKnownBlock(t *testing.T) {
 	if err == nil {
 		t.Fatalf("ProcessBlock for block 3D has no error when expected to have an error\n")
 	}
-	rErr, ok := err.(RuleError)
+	var ruleErr RuleError
+	ok := errors.As(err, &ruleErr)
 	if !ok {
 		t.Fatalf("ProcessBlock for block 3D expected a RuleError, but got %v\n", err)
 	}
-	if !ok || rErr.ErrorCode != ErrDuplicateTxInputs {
+	if !ok || ruleErr.ErrorCode != ErrDuplicateTxInputs {
-		t.Fatalf("ProcessBlock for block 3D expected error code %s but got %s\n", ErrDuplicateTxInputs, rErr.ErrorCode)
+		t.Fatalf("ProcessBlock for block 3D expected error code %s but got %s\n", ErrDuplicateTxInputs, ruleErr.ErrorCode)
 	}
 	if isDelayed {
 		t.Fatalf("ProcessBlock: block 3D " +
@@ -994,7 +996,7 @@ func TestDAGIndexFailedStatus(t *testing.T) {
 	invalidBlock := util.NewBlock(invalidMsgBlock)
 	isOrphan, isDelayed, err := dag.ProcessBlock(invalidBlock, BFNoPoWCheck)
 
-	if _, ok := err.(RuleError); !ok {
+	if !errors.As(err, &RuleError{}) {
 		t.Fatalf("ProcessBlock: expected a rule error but got %s instead", err)
 	}
 	if isDelayed {
@@ -1023,7 +1025,8 @@ func TestDAGIndexFailedStatus(t *testing.T) {
 	invalidBlockChild := util.NewBlock(invalidMsgBlockChild)
 
 	isOrphan, isDelayed, err = dag.ProcessBlock(invalidBlockChild, BFNoPoWCheck)
-	if rErr, ok := err.(RuleError); !ok || rErr.ErrorCode != ErrInvalidAncestorBlock {
+	var ruleErr RuleError
+	if ok := errors.As(err, &ruleErr); !ok || ruleErr.ErrorCode != ErrInvalidAncestorBlock {
 		t.Fatalf("ProcessBlock: expected a rule error but got %s instead", err)
 	}
 	if isDelayed {
@@ -1051,7 +1054,7 @@ func TestDAGIndexFailedStatus(t *testing.T) {
 	invalidBlockGrandChild := util.NewBlock(invalidMsgBlockGrandChild)
 
 	isOrphan, isDelayed, err = dag.ProcessBlock(invalidBlockGrandChild, BFNoPoWCheck)
-	if rErr, ok := err.(RuleError); !ok || rErr.ErrorCode != ErrInvalidAncestorBlock {
+	if ok := errors.As(err, &ruleErr); !ok || ruleErr.ErrorCode != ErrInvalidAncestorBlock {
 		t.Fatalf("ProcessBlock: expected a rule error but got %s instead", err)
 	}
 	if isDelayed {

blockdag/dagio.go

@@ -83,8 +83,8 @@ func (e errNotInDAG) Error() string {
 // isNotInDAGErr returns whether or not the passed error is an
 // errNotInDAG error.
 func isNotInDAGErr(err error) bool {
-	_, ok := err.(errNotInDAG)
+	var notInDAGErr errNotInDAG
-	return ok
+	return errors.As(err, &notInDAGErr)
 }
 
 // errDeserialize signifies that a problem was encountered when deserializing
@@ -99,8 +99,8 @@ func (e errDeserialize) Error() string {
 // isDeserializeErr returns whether or not the passed error is an errDeserialize
 // error.
 func isDeserializeErr(err error) bool {
-	_, ok := err.(errDeserialize)
+	var deserializeErr errDeserialize
-	return ok
+	return errors.As(err, &deserializeErr)
 }
 
 // dbPutVersion uses an existing database transaction to update the provided

blockdag/dagio_test.go

@@ -248,12 +248,13 @@ func TestDAGStateDeserializeErrors(t *testing.T) {
 				test.name, err, test.errType)
 			continue
 		}
-		if derr, ok := err.(database.Error); ok {
+		var dbErr database.Error
+		if ok := errors.As(err, &dbErr); ok {
 			tderr := test.errType.(database.Error)
-			if derr.ErrorCode != tderr.ErrorCode {
+			if dbErr.ErrorCode != tderr.ErrorCode {
 				t.Errorf("deserializeDAGState (%s): "+
 					"wrong error code got: %v, want: %v",
-					test.name, derr.ErrorCode,
+					test.name, dbErr.ErrorCode,
 					tderr.ErrorCode)
 				continue
 			}

blockdag/external_dag_test.go

@@ -137,10 +137,10 @@ func TestFinality(t *testing.T) {
 	if err == nil {
 		t.Errorf("TestFinality: buildNodeToDag expected an error but got <nil>")
 	}
-	rErr, ok := err.(blockdag.RuleError)
+	var ruleErr blockdag.RuleError
-	if ok {
+	if errors.As(err, &ruleErr) {
-		if rErr.ErrorCode != blockdag.ErrFinality {
+		if ruleErr.ErrorCode != blockdag.ErrFinality {
-			t.Errorf("TestFinality: buildNodeToDag expected an error with code %v but instead got %v", blockdag.ErrFinality, rErr.ErrorCode)
+			t.Errorf("TestFinality: buildNodeToDag expected an error with code %v but instead got %v", blockdag.ErrFinality, ruleErr.ErrorCode)
 		}
 	} else {
 		t.Errorf("TestFinality: buildNodeToDag got unexpected error: %v", err)
@@ -152,13 +152,12 @@ func TestFinality(t *testing.T) {
 	if err == nil {
 		t.Errorf("TestFinality: buildNodeToDag expected an error but got <nil>")
 	}
-	rErr, ok = err.(blockdag.RuleError)
+	if errors.As(err, &ruleErr) {
-	if ok {
+		if ruleErr.ErrorCode != blockdag.ErrFinality {
-		if rErr.ErrorCode != blockdag.ErrFinality {
+			t.Errorf("TestFinality: buildNodeToDag expected an error with code %v but instead got %v", blockdag.ErrFinality, ruleErr.ErrorCode)
-			t.Errorf("TestFinality: buildNodeToDag expected an error with code %v but instead got %v", blockdag.ErrFinality, rErr.ErrorCode)
 		}
 	} else {
-		t.Errorf("TestFinality: buildNodeToDag got unexpected error: %v", rErr)
+		t.Errorf("TestFinality: buildNodeToDag got unexpected error: %v", ruleErr)
 	}
 }
 
@@ -269,13 +268,16 @@ func TestChainedTransactions(t *testing.T) {
 	isOrphan, isDelayed, err = dag.ProcessBlock(util.NewBlock(block2), blockdag.BFNoPoWCheck)
 	if err == nil {
 		t.Errorf("ProcessBlock expected an error")
-	} else if rErr, ok := err.(blockdag.RuleError); ok {
+	} else {
-		if rErr.ErrorCode != blockdag.ErrMissingTxOut {
+		var ruleErr blockdag.RuleError
-			t.Errorf("ProcessBlock expected an %v error code but got %v", blockdag.ErrMissingTxOut, rErr.ErrorCode)
+		if ok := errors.As(err, &ruleErr); ok {
+			if ruleErr.ErrorCode != blockdag.ErrMissingTxOut {
+				t.Errorf("ProcessBlock expected an %v error code but got %v", blockdag.ErrMissingTxOut, ruleErr.ErrorCode)
 			}
 		} else {
 			t.Errorf("ProcessBlock expected a blockdag.RuleError but got %v", err)
 		}
+	}
 	if isDelayed {
 		t.Fatalf("ProcessBlock: block2 " +
 			"is too far in the future")
@@ -468,11 +470,11 @@ func TestGasLimit(t *testing.T) {
 	if err == nil {
 		t.Fatalf("ProcessBlock expected to have an error in block that exceeds gas limit")
 	}
-	rErr, ok := err.(blockdag.RuleError)
+	var ruleErr blockdag.RuleError
-	if !ok {
+	if !errors.As(err, &ruleErr) {
 		t.Fatalf("ProcessBlock expected a RuleError, but got %v", err)
-	} else if rErr.ErrorCode != blockdag.ErrInvalidGas {
+	} else if ruleErr.ErrorCode != blockdag.ErrInvalidGas {
-		t.Fatalf("ProcessBlock expected error code %s but got %s", blockdag.ErrInvalidGas, rErr.ErrorCode)
+		t.Fatalf("ProcessBlock expected error code %s but got %s", blockdag.ErrInvalidGas, ruleErr.ErrorCode)
 	}
 	if isDelayed {
 		t.Fatalf("ProcessBlock: overLimitBlock " +
@@ -503,11 +505,10 @@ func TestGasLimit(t *testing.T) {
 	if err == nil {
 		t.Fatalf("ProcessBlock expected to have an error")
 	}
-	rErr, ok = err.(blockdag.RuleError)
+	if !errors.As(err, &ruleErr) {
-	if !ok {
 		t.Fatalf("ProcessBlock expected a RuleError, but got %v", err)
-	} else if rErr.ErrorCode != blockdag.ErrInvalidGas {
+	} else if ruleErr.ErrorCode != blockdag.ErrInvalidGas {
-		t.Fatalf("ProcessBlock expected error code %s but got %s", blockdag.ErrInvalidGas, rErr.ErrorCode)
+		t.Fatalf("ProcessBlock expected error code %s but got %s", blockdag.ErrInvalidGas, ruleErr.ErrorCode)
 	}
 	if isOrphan {
 		t.Fatalf("ProcessBlock: overLimitBlock got unexpectedly orphan")

blockdag/indexers/common.go

@@ -85,8 +85,8 @@ func (e errDeserialize) Error() string {
 // isDeserializeErr returns whether or not the passed error is an errDeserialize
 // error.
 func isDeserializeErr(err error) bool {
-	_, ok := err.(errDeserialize)
+	var deserializeErr errDeserialize
-	return ok
+	return errors.As(err, &deserializeErr)
 }
 
 // internalBucket is an abstraction over a database bucket. It is used to make

blockdag/process.go

@@ -7,6 +7,7 @@ package blockdag
 import (
 	"fmt"
 	"github.com/kaspanet/kaspad/dagconfig"
+	"github.com/pkg/errors"
 	"time"
 
 	"github.com/kaspanet/kaspad/util"
@@ -95,7 +96,8 @@ func (dag *BlockDAG) processOrphans(hash *daghash.Hash, flags BehaviorFlags) err
 			// still missing.
 			_, err := lookupParentNodes(orphan.block, dag)
 			if err != nil {
-				if ruleErr, ok := err.(RuleError); ok && ruleErr.ErrorCode == ErrParentBlockUnknown {
+				var ruleErr RuleError
+				if ok := errors.As(err, &ruleErr); ok && ruleErr.ErrorCode == ErrParentBlockUnknown {
 					continue
 				}
 				return err
@@ -111,7 +113,7 @@ func (dag *BlockDAG) processOrphans(hash *daghash.Hash, flags BehaviorFlags) err
 			if err != nil {
 				// Since we don't want to reject the original block because of
 				// a bad unorphaned child, only return an error if it's not a RuleError.
-				if _, ok := err.(RuleError); !ok {
+				if !errors.As(err, &RuleError{}) {
 					return err
 				}
 				log.Warnf("Verification failed for orphan block %s: %s", orphanHash, err)

blockdag/validate_test.go

@@ -5,6 +5,7 @@
 package blockdag
 
 import (
+	"github.com/pkg/errors"
 	"math"
 	"path/filepath"
 	"testing"
@@ -186,8 +187,8 @@ func TestCheckBlockSanity(t *testing.T) {
 	if err == nil {
 		t.Errorf("CheckBlockSanity: transactions disorder is not detected")
 	}
-	ruleErr, ok := err.(RuleError)
+	var ruleErr RuleError
-	if !ok {
+	if !errors.As(err, &ruleErr) {
 		t.Errorf("CheckBlockSanity: wrong error returned, expect RuleError, got %T", err)
 	} else if ruleErr.ErrorCode != ErrTransactionsNotSorted {
 		t.Errorf("CheckBlockSanity: wrong error returned, expect ErrTransactionsNotSorted, got %v, err %s", ruleErr.ErrorCode, err)
@@ -479,8 +480,10 @@ func TestCheckBlockSanity(t *testing.T) {
 	if err == nil {
 		t.Errorf("CheckBlockSanity: error is nil when it shouldn't be")
 	}
-	rError := err.(RuleError)
+	var rError RuleError
-	if rError.ErrorCode != ErrWrongParentsOrder {
+	if !errors.As(err, &rError) {
+		t.Fatalf("CheckBlockSanity: expected a RuleError, but got %s", err)
+	} else if rError.ErrorCode != ErrWrongParentsOrder {
 		t.Errorf("CheckBlockSanity: Expected error was ErrWrongParentsOrder but got %v", err)
 	}
 	if delay != 0 {

cmd/addblock/addblock.go

@@ -5,6 +5,7 @@
 package main
 
 import (
+	"github.com/pkg/errors"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -37,7 +38,8 @@ func loadBlockDB() (database.DB, error) {
 	if err != nil {
 		// Return the error if it's not because the database doesn't
 		// exist.
-		if dbErr, ok := err.(database.Error); !ok || dbErr.ErrorCode !=
+		var dbErr database.Error
+		if ok := errors.As(err, &dbErr); !ok || dbErr.ErrorCode !=
 			database.ErrDbDoesNotExist {
 
 			return nil, err

cmd/addblock/config.go

@@ -84,7 +84,8 @@ func loadConfig() (*ConfigFlags, []string, error) {
 	parser := flags.NewParser(&activeConfig, flags.Default)
 	remainingArgs, err := parser.Parse()
 	if err != nil {
-		if e, ok := err.(*flags.Error); !ok || e.Type != flags.ErrHelp {
+		var flagsErr *flags.Error
+		if ok := errors.As(err, &flagsErr); !ok || flagsErr.Type != flags.ErrHelp {
 			parser.WriteHelp(os.Stderr)
 		}
 		return nil, nil, err

cmd/addsubnetwork/addsubnetwork.go

@@ -68,7 +68,8 @@ func waitForSubnetworkToBecomeAccepted(client *rpcclient.Client, subnetworkID *s
 	for {
 		_, err := client.GetSubnetwork(subnetworkID.String())
 		if err != nil {
-			if rpcError, ok := err.(*rpcmodel.RPCError); ok && rpcError.Code == rpcmodel.ErrRPCSubnetworkNotFound {
+			var rpcError *rpcmodel.RPCError
+			if ok := errors.As(err, &rpcError); ok && rpcError.Code == rpcmodel.ErrRPCSubnetworkNotFound {
 				log.Infof("Subnetwork not found")
 
 				retries++

cmd/addsubnetwork/utxo.go

@@ -41,7 +41,8 @@ func collectTransactions(client *rpcclient.Client, addrPubKeyHash *util.AddressP
 		results, err := client.SearchRawTransactionsVerbose(addrPubKeyHash, skip, resultsCount, true, false, nil)
 		if err != nil {
 			// Break when there are no further txs
-			if rpcError, ok := err.(*rpcmodel.RPCError); ok && rpcError.Code == rpcmodel.ErrRPCNoTxInfo {
+			var rpcError *rpcmodel.RPCError
+			if ok := errors.As(err, &rpcError); ok && rpcError.Code == rpcmodel.ErrRPCNoTxInfo {
 				break
 			}
 

cmd/gencerts/gencerts.go

@@ -6,6 +6,7 @@ package main
 
 import (
 	"fmt"
+	"github.com/pkg/errors"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -32,7 +33,8 @@ func main() {
 	parser := flags.NewParser(&cfg, flags.Default)
 	_, err := parser.Parse()
 	if err != nil {
-		if e, ok := err.(*flags.Error); !ok || e.Type != flags.ErrHelp {
+		var flagsErr *flags.Error
+		if ok := errors.As(err, &flagsErr); !ok || flagsErr.Type != flags.ErrHelp {
 			parser.WriteHelp(os.Stderr)
 		}
 		return

cmd/kaspactl/config.go

@@ -172,7 +172,8 @@ func loadConfig() (*ConfigFlags, []string, error) {
 	preParser := flags.NewParser(preCfg, flags.HelpFlag)
 	_, err := preParser.Parse()
 	if err != nil {
-		if e, ok := err.(*flags.Error); ok && e.Type == flags.ErrHelp {
+		var flagsErr *flags.Error
+		if ok := errors.As(err, &flagsErr); ok && flagsErr.Type == flags.ErrHelp {
 			fmt.Fprintln(os.Stderr, err)
 			fmt.Fprintln(os.Stderr, "")
 			fmt.Fprintln(os.Stderr, "The special parameter `-` "+
@@ -216,7 +217,7 @@ func loadConfig() (*ConfigFlags, []string, error) {
 	parser := flags.NewParser(activeConfig, flags.Default)
 	err = flags.NewIniParser(parser).ParseFile(preCfg.ConfigFile)
 	if err != nil {
-		if _, ok := err.(*os.PathError); !ok {
+		if pErr := &(os.PathError{}); !errors.As(err, pErr) {
 			fmt.Fprintf(os.Stderr, "Error parsing config file: %s\n",
 				err)
 			fmt.Fprintln(os.Stderr, usageMessage)
@@ -227,7 +228,8 @@ func loadConfig() (*ConfigFlags, []string, error) {
 	// Parse command line options again to ensure they take precedence.
 	remainingArgs, err := parser.Parse()
 	if err != nil {
-		if e, ok := err.(*flags.Error); !ok || e.Type != flags.ErrHelp {
+		var flagsErr *flags.Error
+		if ok := errors.As(err, &flagsErr); !ok || flagsErr.Type != flags.ErrHelp {
 			fmt.Fprintln(os.Stderr, usageMessage)
 		}
 		return nil, nil, err

cmd/kaspactl/kaspactl.go

@@ -5,6 +5,7 @@ import (
 	"bytes"
 	"encoding/json"
 	"fmt"
+	"github.com/pkg/errors"
 	"io"
 	"os"
 	"path/filepath"
@@ -110,9 +111,10 @@ func main() {
 		// rpcmodel.Error as it reallistcally will always be since the
 		// NewCommand function is only supposed to return errors of that
 		// type.
-		if jerr, ok := err.(rpcmodel.Error); ok {
+		var rpcModelErr rpcmodel.Error
+		if ok := errors.As(err, &rpcModelErr); ok {
 			fmt.Fprintf(os.Stderr, "%s error: %s (command code: %s)\n",
-				method, err, jerr.ErrorCode)
+				method, err, rpcModelErr.ErrorCode)
 			commandUsage(method)
 			os.Exit(1)
 		}

config/config.go

@@ -267,7 +267,8 @@ func loadConfig() (*Config, []string, error) {
 	preParser := newConfigParser(&preCfg, &serviceOpts, flags.HelpFlag)
 	_, err := preParser.Parse()
 	if err != nil {
-		if e, ok := err.(*flags.Error); ok && e.Type == flags.ErrHelp {
+		var flagsErr *flags.Error
+		if ok := errors.As(err, &flagsErr); ok && flagsErr.Type == flags.ErrHelp {
 			fmt.Fprintln(os.Stderr, err)
 			return nil, nil, err
 		}
@@ -313,7 +314,7 @@ func loadConfig() (*Config, []string, error) {
 
 		err := flags.NewIniParser(parser).ParseFile(preCfg.ConfigFile)
 		if err != nil {
-			if _, ok := err.(*os.PathError); !ok {
+			if pErr := &(os.PathError{}); !errors.As(err, pErr) {
 				fmt.Fprintf(os.Stderr, "Error parsing config "+
 					"file: %s\n", err)
 				fmt.Fprintln(os.Stderr, usageMessage)
@@ -331,7 +332,8 @@ func loadConfig() (*Config, []string, error) {
 	// Parse command line options again to ensure they take precedence.
 	remainingArgs, err := parser.Parse()
 	if err != nil {
-		if e, ok := err.(*flags.Error); !ok || e.Type != flags.ErrHelp {
+		var flagsErr *flags.Error
+		if ok := errors.As(err, &flagsErr); !ok || flagsErr.Type != flags.ErrHelp {
 			fmt.Fprintln(os.Stderr, usageMessage)
 		}
 		return nil, nil, err
@@ -344,7 +346,8 @@ func loadConfig() (*Config, []string, error) {
 		// Show a nicer error message if it's because a symlink is
 		// linked to a directory that does not exist (probably because
 		// it's not mounted).
-		if e, ok := err.(*os.PathError); ok && os.IsExist(err) {
+		var e *os.PathError
+		if ok := errors.As(err, &e); ok && os.IsExist(err) {
 			if link, lerr := os.Readlink(e.Path); lerr == nil {
 				str := "is symlink %s -> %s mounted?"
 				err = errors.Errorf(str, e.Path, link)

database/cmd/dbtool/insecureimport.go

@@ -370,7 +370,8 @@ func (cmd *importCmd) Execute(args []string) error {
 		resultsChan := importer.Import()
 		results := <-resultsChan
 		if results.err != nil {
-			dbErr, ok := results.err.(database.Error)
+			var dbErr database.Error
+			ok := errors.As(err, dbErr)
 			if !ok || ok && dbErr.ErrorCode != database.ErrDbNotOpen {
 				shutdownChannel <- results.err
 				return

database/cmd/dbtool/main.go

@@ -6,6 +6,7 @@ package main
 
 import (
 	"github.com/kaspanet/kaspad/util/panics"
+	"github.com/pkg/errors"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -39,7 +40,8 @@ func loadBlockDB() (database.DB, error) {
 	if err != nil {
 		// Return the error if it's not because the database doesn't
 		// exist.
-		if dbErr, ok := err.(database.Error); !ok || dbErr.ErrorCode !=
+		var dbErr database.Error
+		if ok := errors.As(err, &dbErr); !ok || dbErr.ErrorCode !=
 			database.ErrDbDoesNotExist {
 
 			return nil, err
@@ -96,7 +98,8 @@ func realMain() error {
 	// Parse command line and invoke the Execute function for the specified
 	// command.
 	if _, err := parser.Parse(); err != nil {
-		if e, ok := err.(*flags.Error); ok && e.Type == flags.ErrHelp {
+		var flagsErr *flags.Error
+		if ok := errors.As(err, &flagsErr); ok && flagsErr.Type == flags.ErrHelp {
 			parser.WriteHelp(os.Stderr)
 		} else {
 			log.Error(err)

database/error.go

@@ -4,7 +4,10 @@
 
 package database
 
-import "fmt"
+import (
+	"fmt"
+	"github.com/pkg/errors"
+)
 
 // ErrorCode identifies a kind of error.
 type ErrorCode int
@@ -199,8 +202,9 @@ func makeError(c ErrorCode, desc string, err error) Error {
 // IsErrorCode returns whether or not the provided error is a script error with
 // the provided error code.
 func IsErrorCode(err error, c ErrorCode) bool {
-	if err, ok := err.(Error); ok {
+	var errError Error
-		return err.ErrorCode == c
+	if ok := errors.As(err, &errError); ok {
+		return errError.ErrorCode == c
 	}
 
 	return false

database/ffldb/blockio.go

@@ -11,6 +11,7 @@ import (
 	"container/list"
 	"encoding/binary"
 	"fmt"
+	"github.com/pkg/errors"
 	"hash/crc32"
 	"io"
 	"os"
@@ -379,7 +380,8 @@ func (s *blockStore) writeData(data []byte, fieldName string) error {
 	n, err := wc.curFile.file.WriteAt(data, int64(wc.curOffset))
 	wc.curOffset += uint32(n)
 	if err != nil {
-		if pathErr, isOk := err.(*os.PathError); isOk && pathErr.Err == syscall.ENOSPC {
+		var pathErr *os.PathError
+		if ok := errors.As(err, &pathErr); ok && pathErr.Err == syscall.ENOSPC {
 			log.Errorf("No space left on the hard disk, exiting...")
 			os.Exit(1)
 		}

go.mod

@@ -15,7 +15,7 @@ require (
 	github.com/jessevdk/go-flags v1.4.0
 	github.com/jrick/logrotate v1.0.0
 	github.com/kr/pretty v0.1.0 // indirect
-	github.com/pkg/errors v0.8.1
+	github.com/pkg/errors v0.9.1
 	golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550
 	golang.org/x/net v0.0.0-20190620200207-3b0461eec859 // indirect
 	golang.org/x/sys v0.0.0-20190426135247-a129542de9ae // indirect

go.sum

@@ -33,6 +33,8 @@ github.com/onsi/gomega v1.4.1 h1:PZSj/UFNaVp3KxrzHOcS7oyuWA7LoOY/77yCTEFu21U=
 github.com/onsi/gomega v1.4.1/go.mod h1:C1qb7wdrVGGVU+Z6iS04AVkA3Q65CEZX59MT0QO5uiA=
 github.com/pkg/errors v0.8.1 h1:iURUrRGxPUNPdy5/HRSm+Yj6okJ6UtLINN0Q9M4+h3I=
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
+github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550 h1:ObdrDkeb4kJdCP557AjRjq69pTHfNouLtWZG7j9rPN8=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=

kaspad.go

@@ -6,6 +6,7 @@ package main
 
 import (
 	"fmt"
+	"github.com/pkg/errors"
 	"net"
 	"net/http"
 	_ "net/http/pprof"
@@ -293,7 +294,8 @@ func loadBlockDB() (database.DB, error) {
 	if err != nil {
 		// Return the error if it's not because the database doesn't
 		// exist.
-		if dbErr, ok := err.(database.Error); !ok || dbErr.ErrorCode !=
+		var dbErr database.Error
+		if ok := errors.As(err, &dbErr); !ok || dbErr.ErrorCode !=
 			database.ErrDbDoesNotExist {
 
 			return nil, err

mempool/error.go

@@ -7,6 +7,7 @@ package mempool
 import (
 	"github.com/kaspanet/kaspad/blockdag"
 	"github.com/kaspanet/kaspad/wire"
+	"github.com/pkg/errors"
 )
 
 // RuleError identifies a rule violation. It is used to indicate that
@@ -63,15 +64,16 @@ func dagRuleError(dagErr blockdag.RuleError) RuleError {
 // was successfully extracted.
 func extractRejectCode(err error) (wire.RejectCode, bool) {
 	// Pull the underlying error out of a RuleError.
-	if rerr, ok := err.(RuleError); ok {
+	var ruleErr RuleError
-		err = rerr.Err
+	if ok := errors.As(err, &ruleErr); ok {
+		err = ruleErr.Err
 	}
 
-	switch err := err.(type) {
+	var dagRuleErr blockdag.RuleError
-	case blockdag.RuleError:
+	if errors.As(err, &dagRuleErr) {
 		// Convert the DAG error to a reject code.
 		var code wire.RejectCode
-		switch err.ErrorCode {
+		switch dagRuleErr.ErrorCode {
 		// Rejected due to duplicate.
 		case blockdag.ErrDuplicateBlock:
 			code = wire.RejectDuplicate
@@ -92,11 +94,14 @@ func extractRejectCode(err error) (wire.RejectCode, bool) {
 		}
 
 		return code, true
+	}
 
-	case TxRuleError:
+	var trErr TxRuleError
-		return err.RejectCode, true
+	if errors.As(err, &trErr) {
+		return trErr.RejectCode, true
+	}
 
-	case nil:
+	if err == nil {
 		return wire.RejectInvalid, false
 	}
 

mempool/mempool.go

@@ -811,8 +811,9 @@ func (mp *TxPool) maybeAcceptTransaction(tx *util.Tx, rejectDupOrphans bool) ([]
 	// transactions are allowed into blocks.
 	err := blockdag.CheckTransactionSanity(tx, subnetworkID)
 	if err != nil {
-		if cerr, ok := err.(blockdag.RuleError); ok {
+		var ruleErr blockdag.RuleError
-			return nil, nil, dagRuleError(cerr)
+		if ok := errors.As(err, &ruleErr); ok {
+			return nil, nil, dagRuleError(ruleErr)
 		}
 		return nil, nil, err
 	}
@@ -918,8 +919,9 @@ func (mp *TxPool) maybeAcceptTransaction(tx *util.Tx, rejectDupOrphans bool) ([]
 	// with respect to its defined relative lock times.
 	sequenceLock, err := mp.cfg.CalcSequenceLockNoLock(tx, mp.mpUTXOSet)
 	if err != nil {
-		if cerr, ok := err.(blockdag.RuleError); ok {
+		var dagRuleErr blockdag.RuleError
-			return nil, nil, dagRuleError(cerr)
+		if ok := errors.As(err, &dagRuleErr); ok {
+			return nil, nil, dagRuleError(dagRuleErr)
 		}
 		return nil, nil, err
 	}
@@ -933,7 +935,8 @@ func (mp *TxPool) maybeAcceptTransaction(tx *util.Tx, rejectDupOrphans bool) ([]
 	// transaction mass.
 	err = blockdag.ValidateTxMass(tx, mp.mpUTXOSet)
 	if err != nil {
-		if ruleError, ok := err.(blockdag.RuleError); ok {
+		var ruleError blockdag.RuleError
+		if ok := errors.As(err, &ruleError); ok {
 			return nil, nil, dagRuleError(ruleError)
 		}
 		return nil, nil, err
@@ -946,8 +949,9 @@ func (mp *TxPool) maybeAcceptTransaction(tx *util.Tx, rejectDupOrphans bool) ([]
 	txFee, err := blockdag.CheckTransactionInputsAndCalulateFee(tx, nextBlockBlueScore,
 		mp.mpUTXOSet, mp.cfg.DAGParams, false)
 	if err != nil {
-		if cerr, ok := err.(blockdag.RuleError); ok {
+		var dagRuleErr blockdag.RuleError
-			return nil, nil, dagRuleError(cerr)
+		if ok := errors.As(err, &dagRuleErr); ok {
+			return nil, nil, dagRuleError(dagRuleErr)
 		}
 		return nil, nil, err
 	}
@@ -1006,8 +1010,9 @@ func (mp *TxPool) maybeAcceptTransaction(tx *util.Tx, rejectDupOrphans bool) ([]
 	err = blockdag.ValidateTransactionScripts(tx, mp.mpUTXOSet,
 		txscript.StandardVerifyFlags, mp.cfg.SigCache)
 	if err != nil {
-		if cerr, ok := err.(blockdag.RuleError); ok {
+		var dagRuleErr blockdag.RuleError
-			return nil, nil, dagRuleError(cerr)
+		if ok := errors.As(err, &dagRuleErr); ok {
+			return nil, nil, dagRuleError(dagRuleErr)
 		}
 		return nil, nil, err
 	}

mempool/policy_test.go

@@ -6,6 +6,7 @@ package mempool
 
 import (
 	"bytes"
+	"github.com/pkg/errors"
 	"testing"
 	"time"
 
@@ -313,24 +314,24 @@ func TestCheckTransactionStandard(t *testing.T) {
 		}
 
 		// Ensure error type is a TxRuleError inside of a RuleError.
-		rerr, ok := err.(RuleError)
+		var ruleErr RuleError
-		if !ok {
+		if !errors.As(err, &ruleErr) {
 			t.Errorf("checkTransactionStandard (%s): unexpected "+
 				"error type - got %T", test.name, err)
 			continue
 		}
-		txrerr, ok := rerr.Err.(TxRuleError)
+		txRuleErr, ok := ruleErr.Err.(TxRuleError)
 		if !ok {
 			t.Errorf("checkTransactionStandard (%s): unexpected "+
-				"error type - got %T", test.name, rerr.Err)
+				"error type - got %T", test.name, ruleErr.Err)
 			continue
 		}
 
 		// Ensure the reject code is the expected one.
-		if txrerr.RejectCode != test.code {
+		if txRuleErr.RejectCode != test.code {
 			t.Errorf("checkTransactionStandard (%s): unexpected "+
 				"error code - got %v, want %v", test.name,
-				txrerr.RejectCode, test.code)
+				txRuleErr.RejectCode, test.code)
 			continue
 		}
 	}

netsync/manager.go

@@ -392,7 +392,7 @@ func (sm *SyncManager) handleTxMsg(tmsg *txMsg) {
 		// simply rejected as opposed to something actually going wrong,
 		// so log it as such. Otherwise, something really did go wrong,
 		// so log it as an actual error.
-		if _, ok := err.(mempool.RuleError); ok {
+		if errors.As(err, &mempool.RuleError{}) {
 			log.Debugf("Rejected transaction %s from %s: %s",
 				txID, peer, err)
 		} else {
@@ -491,14 +491,15 @@ func (sm *SyncManager) handleBlockMsg(bmsg *blockMsg) {
 		// rejected as opposed to something actually going wrong, so log
 		// it as such. Otherwise, something really did go wrong, so log
 		// it as an actual error.
-		if _, ok := err.(blockdag.RuleError); ok {
+		if errors.As(err, &blockdag.RuleError{}) {
 			log.Infof("Rejected block %s from %s: %s", blockHash,
 				peer, err)
 		} else {
 			log.Errorf("Failed to process block %s: %s",
 				blockHash, err)
 		}
-		if dbErr, ok := err.(database.Error); ok && dbErr.ErrorCode ==
+		var dbErr database.Error
+		if ok := errors.As(err, &dbErr); ok && dbErr.ErrorCode ==
 			database.ErrCorruption {
 			panic(dbErr)
 		}

peer/peer.go

@@ -1113,7 +1113,7 @@ func (p *Peer) isAllowedReadError(err error) bool {
 	}
 
 	// Don't allow the error if it's not specifically a malformed message error.
-	if _, ok := err.(*wire.MessageError); !ok {
+	if msgErr := &(wire.MessageError{}); !errors.As(err, &msgErr) {
 		return false
 	}
 
@@ -1147,7 +1147,8 @@ func (p *Peer) shouldHandleReadError(err error) bool {
 	if err == io.EOF {
 		return false
 	}
-	if opErr, ok := err.(*net.OpError); ok && !opErr.Temporary() {
+	var opErr *net.OpError
+	if ok := errors.As(err, &opErr); ok && !opErr.Temporary() {
 		return false
 	}
 

rpcclient/doc.go

@@ -121,8 +121,9 @@ detect if a command is unimplemented by the remote RPC server:
 
   netTotals, err := client.GetNetTotals()
   if err != nil {
-  	if jerr, ok := err.(*rpcmodel.RPCError); ok {
+	var jErr *rpcmodel.RPCError
-  		switch jerr.Code {
+  	if errors.As(err, jErr) {
+  		switch jErr.Code {
   		case rpcmodel.ErrRPCUnimplemented:
   			// Handle not implemented error
 

rpcclient/infrastructure.go

@@ -395,7 +395,8 @@ func (c *Client) shouldLogReadError(err error) bool {
 	if err == io.EOF {
 		return false
 	}
-	if opErr, ok := err.(*net.OpError); ok && !opErr.Temporary() {
+	var opErr *net.OpError
+	if ok := errors.As(err, &opErr); ok && !opErr.Temporary() {
 		return false
 	}
 

rpcmodel/command_info_test.go

@@ -5,6 +5,7 @@
 package rpcmodel_test
 
 import (
+	"github.com/pkg/errors"
 	"reflect"
 	"testing"
 
@@ -48,12 +49,17 @@ func TestCommandMethod(t *testing.T) {
 			continue
 		}
 		if err != nil {
-			gotErrorCode := err.(rpcmodel.Error).ErrorCode
+			var gotRPCModelErr rpcmodel.Error
-			if gotErrorCode != test.err.(rpcmodel.Error).ErrorCode {
+			errors.As(err, &gotRPCModelErr)
+			gotErrorCode := gotRPCModelErr.ErrorCode
+			var testRPCModelErr rpcmodel.Error
+			errors.As(err, &testRPCModelErr)
+			testErrorCode := testRPCModelErr.ErrorCode
+			if gotErrorCode != testErrorCode {
 				t.Errorf("Test #%d (%s) mismatched error code "+
 					"- got %v (%v), want %v", i, test.name,
 					gotErrorCode, err,
-					test.err.(rpcmodel.Error).ErrorCode)
+					testErrorCode)
 				continue
 			}
 
@@ -101,12 +107,17 @@ func TestMethodUsageFlags(t *testing.T) {
 			continue
 		}
 		if err != nil {
-			gotErrorCode := err.(rpcmodel.Error).ErrorCode
+			var gotRPCModelErr rpcmodel.Error
-			if gotErrorCode != test.err.(rpcmodel.Error).ErrorCode {
+			errors.As(err, &gotRPCModelErr)
+			gotErrorCode := gotRPCModelErr.ErrorCode
+			var testRPCModelErr rpcmodel.Error
+			errors.As(err, &testRPCModelErr)
+			testErrorCode := testRPCModelErr.ErrorCode
+			if gotErrorCode != testErrorCode {
 				t.Errorf("Test #%d (%s) mismatched error code "+
 					"- got %v (%v), want %v", i, test.name,
 					gotErrorCode, err,
-					test.err.(rpcmodel.Error).ErrorCode)
+					testErrorCode)
 				continue
 			}
 
@@ -159,12 +170,17 @@ func TestMethodUsageText(t *testing.T) {
 			continue
 		}
 		if err != nil {
-			gotErrorCode := err.(rpcmodel.Error).ErrorCode
+			var gotRPCModelErr rpcmodel.Error
-			if gotErrorCode != test.err.(rpcmodel.Error).ErrorCode {
+			errors.As(err, &gotRPCModelErr)
+			gotErrorCode := gotRPCModelErr.ErrorCode
+			var testRPCModelErr rpcmodel.Error
+			errors.As(err, &testRPCModelErr)
+			testErrorCode := testRPCModelErr.ErrorCode
+			if gotErrorCode != testErrorCode {
 				t.Errorf("Test #%d (%s) mismatched error code "+
 					"- got %v (%v), want %v", i, test.name,
 					gotErrorCode, err,
-					test.err.(rpcmodel.Error).ErrorCode)
+					testErrorCode)
 				continue
 			}
 

rpcmodel/command_parse.go

@@ -7,6 +7,7 @@ package rpcmodel
 import (
 	"encoding/json"
 	"fmt"
+	"github.com/pkg/errors"
 	"reflect"
 	"strconv"
 	"strings"
@@ -136,10 +137,11 @@ func UnmarshalCommand(r *Request) (interface{}, error) {
 			// The most common error is the wrong type, so
 			// explicitly detect that error and make it nicer.
 			fieldName := strings.ToLower(rt.Field(i).Name)
-			if jerr, ok := err.(*json.UnmarshalTypeError); ok {
+			var jsonErr *json.UnmarshalTypeError
+			if ok := errors.As(err, &jsonErr); ok {
 				str := fmt.Sprintf("parameter #%d '%s' must "+
 					"be type %s (got %s)", i+1, fieldName,
-					jerr.Type, jerr.Value)
+					jsonErr.Type, jsonErr.Value)
 				return nil, makeError(ErrInvalidType, str)
 			}
 

rpcmodel/command_parse_test.go

@@ -6,6 +6,7 @@ package rpcmodel_test
 
 import (
 	"encoding/json"
+	"github.com/pkg/errors"
 	"math"
 	"reflect"
 	"testing"
@@ -337,7 +338,9 @@ func TestAssignFieldErrors(t *testing.T) {
 				"want %T", i, test.name, err, test.err)
 			continue
 		}
-		gotErrorCode := err.(rpcmodel.Error).ErrorCode
+		var gotRPCModelErr rpcmodel.Error
+		errors.As(err, &gotRPCModelErr)
+		gotErrorCode := gotRPCModelErr.ErrorCode
 		if gotErrorCode != test.err.ErrorCode {
 			t.Errorf("Test #%d (%s) mismatched error code - got "+
 				"%v (%v), want %v", i, test.name, gotErrorCode,
@@ -391,7 +394,9 @@ func TestNewCommandErrors(t *testing.T) {
 				"want %T", i, test.name, err, test.err)
 			continue
 		}
-		gotErrorCode := err.(rpcmodel.Error).ErrorCode
+		var gotRPCModelErr rpcmodel.Error
+		errors.As(err, &gotRPCModelErr)
+		gotErrorCode := gotRPCModelErr.ErrorCode
 		if gotErrorCode != test.err.ErrorCode {
 			t.Errorf("Test #%d (%s) mismatched error code - got "+
 				"%v (%v), want %v", i, test.name, gotErrorCode,
@@ -439,7 +444,9 @@ func TestMarshalCommandErrors(t *testing.T) {
 				"want %T", i, test.name, err, test.err)
 			continue
 		}
-		gotErrorCode := err.(rpcmodel.Error).ErrorCode
+		var gotRPCModelErr rpcmodel.Error
+		errors.As(err, &gotRPCModelErr)
+		gotErrorCode := gotRPCModelErr.ErrorCode
 		if gotErrorCode != test.err.ErrorCode {
 			t.Errorf("Test #%d (%s) mismatched error code - got "+
 				"%v (%v), want %v", i, test.name, gotErrorCode,
@@ -508,7 +515,9 @@ func TestUnmarshalCommandErrors(t *testing.T) {
 				"want %T", i, test.name, err, test.err)
 			continue
 		}
-		gotErrorCode := err.(rpcmodel.Error).ErrorCode
+		var gotRPCModelErr rpcmodel.Error
+		errors.As(err, &gotRPCModelErr)
+		gotErrorCode := gotRPCModelErr.ErrorCode
 		if gotErrorCode != test.err.ErrorCode {
 			t.Errorf("Test #%d (%s) mismatched error code - got "+
 				"%v (%v), want %v", i, test.name, gotErrorCode,

rpcmodel/help_test.go

@@ -5,6 +5,7 @@
 package rpcmodel_test
 
 import (
+	"github.com/pkg/errors"
 	"reflect"
 	"testing"
 
@@ -703,7 +704,9 @@ func TestGenerateHelpErrors(t *testing.T) {
 				"want %T", i, test.name, err, test.err)
 			continue
 		}
-		gotErrorCode := err.(rpcmodel.Error).ErrorCode
+		var gotRPCModelErr rpcmodel.Error
+		errors.As(err, &gotRPCModelErr)
+		gotErrorCode := gotRPCModelErr.ErrorCode
 		if gotErrorCode != test.err.ErrorCode {
 			t.Errorf("Test #%d (%s) mismatched error code - got "+
 				"%v (%v), want %v", i, test.name, gotErrorCode,

rpcmodel/jsonrpc_test.go

@@ -6,6 +6,7 @@ package rpcmodel_test
 
 import (
 	"encoding/json"
+	"github.com/pkg/errors"
 	"reflect"
 	"testing"
 
@@ -114,7 +115,8 @@ func TestMiscErrors(t *testing.T) {
 	// supported.
 	wantErr := rpcmodel.Error{ErrorCode: rpcmodel.ErrInvalidType}
 	_, err = rpcmodel.MarshalResponse(make(chan int), nil, nil)
-	if jerr, ok := err.(rpcmodel.Error); !ok || jerr.ErrorCode != wantErr.ErrorCode {
+	var rpcModelErr rpcmodel.Error
+	if ok := errors.As(err, &rpcModelErr); !ok || rpcModelErr.ErrorCode != wantErr.ErrorCode {
 		t.Errorf("MarshalResult: did not receive expected error - got "+
 			"%v (%[1]T), want %v (%[2]T)", err, wantErr)
 		return
@@ -123,7 +125,7 @@ func TestMiscErrors(t *testing.T) {
 	// Force an error in MarshalResponse by giving it a result type that
 	// can't be marshalled.
 	_, err = rpcmodel.MarshalResponse(1, make(chan int), nil)
-	if _, ok := err.(*json.UnsupportedTypeError); !ok {
+	if jErr := &(json.UnsupportedTypeError{}); !errors.As(err, &jErr) {
 		wantErr := &json.UnsupportedTypeError{}
 		t.Errorf("MarshalResult: did not receive expected error - got "+
 			"%v (%[1]T), want %T", err, wantErr)

rpcmodel/register_test.go

@@ -5,6 +5,7 @@
 package rpcmodel_test
 
 import (
+	"github.com/pkg/errors"
 	"reflect"
 	"sort"
 	"testing"
@@ -214,7 +215,9 @@ func TestRegisterCmdErrors(t *testing.T) {
 				"want %T", i, test.name, err, test.err)
 			continue
 		}
-		gotErrorCode := err.(rpcmodel.Error).ErrorCode
+		var gotRPCModelErr rpcmodel.Error
+		errors.As(err, &gotRPCModelErr)
+		gotErrorCode := gotRPCModelErr.ErrorCode
 		if gotErrorCode != test.err.ErrorCode {
 			t.Errorf("Test #%d (%s) mismatched error code - got "+
 				"%v, want %v", i, test.name, gotErrorCode,

rpcmodel/rpc_commands_test.go

@@ -7,6 +7,7 @@ package rpcmodel_test
 import (
 	"bytes"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"reflect"
 	"testing"
@@ -1122,12 +1123,15 @@ func TestRPCServerCommandErrors(t *testing.T) {
 			continue
 		}
 
-		if terr, ok := test.err.(rpcmodel.Error); ok {
+		var testErr rpcmodel.Error
-			gotErrorCode := err.(rpcmodel.Error).ErrorCode
+		if errors.As(err, &testErr) {
-			if gotErrorCode != terr.ErrorCode {
+			var gotRPCModelErr rpcmodel.Error
+			errors.As(err, &gotRPCModelErr)
+			gotErrorCode := gotRPCModelErr.ErrorCode
+			if gotErrorCode != testErr.ErrorCode {
 				t.Errorf("Test #%d (%s) mismatched error code "+
 					"- got %v (%v), want %v", i, test.name,
-					gotErrorCode, terr, terr.ErrorCode)
+					gotErrorCode, testErr, testErr.ErrorCode)
 				continue
 			}
 		}

server/rpc/handle_get_block_template.go

@@ -343,7 +343,7 @@ func handleGetBlockTemplateProposal(s *Server, request *rpcmodel.TemplateRequest
 	}
 
 	if err := s.cfg.DAG.CheckConnectBlockTemplate(block); err != nil {
-		if _, ok := err.(blockdag.RuleError); !ok {
+		if !errors.As(err, &blockdag.RuleError{}) {
 			errStr := fmt.Sprintf("Failed to process block proposal: %s", err)
 			log.Error(errStr)
 			return nil, &rpcmodel.RPCError{
@@ -365,8 +365,8 @@ func handleGetBlockTemplateProposal(s *Server, request *rpcmodel.TemplateRequest
 func dagErrToGBTErrString(err error) string {
 	// When the passed error is not a RuleError, just return a generic
 	// rejected string with the error text.
-	ruleErr, ok := err.(blockdag.RuleError)
+	var ruleErr blockdag.RuleError
-	if !ok {
+	if !errors.As(err, &ruleErr) {
 		return "rejected: " + err.Error()
 	}
 

server/rpc/handle_send_raw_transaction.go

@@ -9,6 +9,7 @@ import (
 	"github.com/kaspanet/kaspad/util"
 	"github.com/kaspanet/kaspad/util/daghash"
 	"github.com/kaspanet/kaspad/wire"
+	"github.com/pkg/errors"
 )
 
 // handleSendRawTransaction implements the sendRawTransaction command.
@@ -42,7 +43,7 @@ func handleSendRawTransaction(s *Server, cmd interface{}, closeChan <-chan struc
 		// so log it as an actual error. In both cases, a JSON-RPC
 		// error is returned to the client with the deserialization
 		// error code
-		if _, ok := err.(mempool.RuleError); ok {
+		if errors.As(err, &mempool.RuleError{}) {
 			log.Debugf("Rejected transaction %s: %s", tx.ID(),
 				err)
 		} else {

server/rpc/rpcserver.go

@@ -393,8 +393,9 @@ func parseCmd(request *rpcmodel.Request) *parsedRPCCmd {
 	if err != nil {
 		// When the error is because the method is not registered,
 		// produce a method not found RPC error.
-		if jerr, ok := err.(rpcmodel.Error); ok &&
+		var rpcModelErr rpcmodel.Error
-			jerr.ErrorCode == rpcmodel.ErrUnregisteredMethod {
+		if ok := errors.As(err, &rpcModelErr); ok &&
+			rpcModelErr.ErrorCode == rpcmodel.ErrUnregisteredMethod {
 
 			parsedCmd.err = rpcmodel.ErrRPCMethodNotFound
 			return &parsedCmd
@@ -610,7 +611,7 @@ func (s *Server) Start() {
 		// using the default size for read/write buffers.
 		ws, err := websocket.Upgrade(w, r, nil, 0, 0)
 		if err != nil {
-			if _, ok := err.(websocket.HandshakeError); !ok {
+			if !errors.As(err, &websocket.HandshakeError{}) {
 				log.Errorf("Unexpected websocket error: %s",
 					err)
 			}

txscript/error.go

@@ -6,6 +6,7 @@ package txscript
 
 import (
 	"fmt"
+	"github.com/pkg/errors"
 )
 
 // ErrorCode identifies a kind of script error.
@@ -308,8 +309,9 @@ func scriptError(c ErrorCode, desc string) Error {
 // IsErrorCode returns whether or not the provided error is a script error with
 // the provided error code.
 func IsErrorCode(err error, c ErrorCode) bool {
-	if err, ok := err.(Error); ok {
+	var errError Error
-		return err.ErrorCode == c
+	if ok := errors.As(err, &errError); ok {
+		return errError.ErrorCode == c
 	}
 
 	return false

txscript/reference_test.go

@@ -334,9 +334,10 @@ func testScripts(t *testing.T, tests [][]interface{}, useSigCache bool) {
 			}
 		}
 		if !success {
-			if serr, ok := err.(Error); ok {
+			var scriptErr Error
+			if ok := errors.As(err, &scriptErr); ok {
 				t.Errorf("%s: want error codes %v, got %v", name,
-					allowedErrorCodes, serr.ErrorCode)
+					allowedErrorCodes, scriptErr.ErrorCode)
 				continue
 			}
 			t.Errorf("%s: want error codes %v, got err: %v (%T)",

txscript/scriptbuilder_test.go

@@ -6,6 +6,7 @@ package txscript
 
 import (
 	"bytes"
+	"github.com/pkg/errors"
 	"testing"
 )
 
@@ -300,7 +301,8 @@ func TestExceedMaxScriptSize(t *testing.T) {
 	// Ensure adding data that would exceed the maximum size of the script
 	// does not add the data.
 	script, err := builder.AddData([]byte{0x00}).Script()
-	if _, ok := err.(ErrScriptNotCanonical); !ok || err == nil {
+	var errScriptNotCanonical ErrScriptNotCanonical
+	if !errors.As(err, &errScriptNotCanonical) || err == nil {
 		t.Fatalf("ScriptBuilder.AddData allowed exceeding max script "+
 			"size: %v", len(script))
 	}
@@ -313,7 +315,7 @@ func TestExceedMaxScriptSize(t *testing.T) {
 	// script does not add the data.
 	builder.Reset().AddFullData(make([]byte, MaxScriptSize-3))
 	script, err = builder.AddOp(Op0).Script()
-	if _, ok := err.(ErrScriptNotCanonical); !ok || err == nil {
+	if !errors.As(err, &errScriptNotCanonical) || err == nil {
 		t.Fatalf("ScriptBuilder.AddOp unexpected modified script - "+
 			"got len %d, want len %d", len(script), len(origScript))
 	}
@@ -326,7 +328,7 @@ func TestExceedMaxScriptSize(t *testing.T) {
 	// script does not add the data.
 	builder.Reset().AddFullData(make([]byte, MaxScriptSize-3))
 	script, err = builder.AddInt64(0).Script()
-	if _, ok := err.(ErrScriptNotCanonical); !ok || err == nil {
+	if !errors.As(err, &errScriptNotCanonical) || err == nil {
 		t.Fatalf("ScriptBuilder.AddInt64 unexpected modified script - "+
 			"got len %d, want len %d", len(script), len(origScript))
 	}
@@ -351,7 +353,8 @@ func TestErroredScript(t *testing.T) {
 		t.Fatalf("ScriptBuilder.AddFullData unexpected error: %v", err)
 	}
 	script, err := builder.AddData([]byte{0x00, 0x00, 0x00, 0x00, 0x00}).Script()
-	if _, ok := err.(ErrScriptNotCanonical); !ok || err == nil {
+	var errScriptNotCanonical ErrScriptNotCanonical
+	if !errors.As(err, &errScriptNotCanonical) || err == nil {
 		t.Fatalf("ScriptBuilder.AddData allowed exceeding max script "+
 			"size: %v", len(script))
 	}
@@ -363,7 +366,7 @@ func TestErroredScript(t *testing.T) {
 	// Ensure adding data, even using the non-canonical path, to a script
 	// that has errored doesn't succeed.
 	script, err = builder.AddFullData([]byte{0x00}).Script()
-	if _, ok := err.(ErrScriptNotCanonical); !ok || err == nil {
+	if !errors.As(err, &errScriptNotCanonical) || err == nil {
 		t.Fatal("ScriptBuilder.AddFullData succeeded on errored script")
 	}
 	if !bytes.Equal(script, origScript) {
@@ -374,7 +377,7 @@ func TestErroredScript(t *testing.T) {
 
 	// Ensure adding data to a script that has errored doesn't succeed.
 	script, err = builder.AddData([]byte{0x00}).Script()
-	if _, ok := err.(ErrScriptNotCanonical); !ok || err == nil {
+	if !errors.As(err, &errScriptNotCanonical) || err == nil {
 		t.Fatal("ScriptBuilder.AddData succeeded on errored script")
 	}
 	if !bytes.Equal(script, origScript) {
@@ -385,7 +388,7 @@ func TestErroredScript(t *testing.T) {
 
 	// Ensure adding an opcode to a script that has errored doesn't succeed.
 	script, err = builder.AddOp(Op0).Script()
-	if _, ok := err.(ErrScriptNotCanonical); !ok || err == nil {
+	if !errors.As(err, &errScriptNotCanonical) || err == nil {
 		t.Fatal("ScriptBuilder.AddOp succeeded on errored script")
 	}
 	if !bytes.Equal(script, origScript) {
@@ -396,7 +399,7 @@ func TestErroredScript(t *testing.T) {
 	// Ensure adding an integer to a script that has errored doesn't
 	// succeed.
 	script, err = builder.AddInt64(0).Script()
-	if _, ok := err.(ErrScriptNotCanonical); !ok || err == nil {
+	if !errors.As(err, &errScriptNotCanonical) || err == nil {
 		t.Fatal("ScriptBuilder.AddInt64 succeeded on errored script")
 	}
 	if !bytes.Equal(script, origScript) {

util/block_test.go

@@ -6,6 +6,7 @@ package util_test
 
 import (
 	"bytes"
+	"github.com/pkg/errors"
 	"io"
 	"math"
 	"reflect"
@@ -260,24 +261,25 @@ func TestBlockErrors(t *testing.T) {
 
 	// Ensure TxHash returns expected error on invalid indices.
 	_, err = b.TxHash(-1)
-	if _, ok := err.(util.OutOfRangeError); !ok {
+	var outOfRangeErr util.OutOfRangeError
+	if !errors.As(err, &outOfRangeErr) {
 		t.Errorf("TxHash: wrong error - got: %v <%T>, "+
 			"want: <%T>", err, err, util.OutOfRangeError(""))
 	}
 	_, err = b.TxHash(len(Block100000.Transactions) + 1)
-	if _, ok := err.(util.OutOfRangeError); !ok {
+	if !errors.As(err, &outOfRangeErr) {
 		t.Errorf("TxHash: wrong error - got: %v <%T>, "+
 			"want: <%T>", err, err, util.OutOfRangeError(""))
 	}
 
 	// Ensure Tx returns expected error on invalid indices.
 	_, err = b.Tx(-1)
-	if _, ok := err.(util.OutOfRangeError); !ok {
+	if !errors.As(err, &outOfRangeErr) {
 		t.Errorf("Tx: wrong error - got: %v <%T>, "+
 			"want: <%T>", err, err, util.OutOfRangeError(""))
 	}
 	_, err = b.Tx(len(Block100000.Transactions) + 1)
-	if _, ok := err.(util.OutOfRangeError); !ok {
+	if !errors.As(err, &outOfRangeErr) {
 		t.Errorf("Tx: wrong error - got: %v <%T>, "+
 			"want: <%T>", err, err, util.OutOfRangeError(""))
 	}

util/daghash/hash_test.go

@@ -7,7 +7,7 @@ package daghash
 import (
 	"bytes"
 	"encoding/hex"
-	"github.com/kaspanet/kaspad/testutil"
+	"errors"
 	"math/big"
 	"reflect"
 	"testing"
@@ -215,7 +215,7 @@ func TestNewHashFromStr(t *testing.T) {
 	t.Logf("Running %d tests", len(tests))
 	for i, test := range tests {
 		result, err := NewHashFromStr(test.in)
-		if !testutil.AreErrorsEqual(err, test.err) {
+		if !errors.Is(err, test.err) {
 			t.Errorf(unexpectedErrStr, i, err, test.err)
 			continue
 		} else if err != nil {

wire/common_test.go

@@ -6,6 +6,7 @@ package wire
 
 import (
 	"bytes"
+	"github.com/pkg/errors"
 	"io"
 	"reflect"
 	"strings"
@@ -397,7 +398,7 @@ func TestVarIntNonCanonical(t *testing.T) {
 		// Decode from wire format.
 		rbuf := bytes.NewReader(test.in)
 		val, err := ReadVarInt(rbuf)
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			t.Errorf("ReadVarInt #%d (%s) unexpected error %v", i,
 				test.name, err)
 			continue

wire/message_test.go

@@ -7,6 +7,7 @@ package wire
 import (
 	"bytes"
 	"encoding/binary"
+	"github.com/pkg/errors"
 	"io"
 	"net"
 	"reflect"
@@ -360,7 +361,7 @@ func TestReadMessageWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.readErr {
 				t.Errorf("ReadMessage #%d wrong error got: %v <%T>, "+
 					"want: %v <%T>", i, err, err,
@@ -438,7 +439,7 @@ func TestWriteMessageWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.err {
 				t.Errorf("ReadMessage #%d wrong error got: %v <%T>, "+
 					"want: %v <%T>", i, err, err,

wire/msgaddr_test.go

@@ -6,6 +6,7 @@ package wire
 
 import (
 	"bytes"
+	"github.com/pkg/errors"
 	"io"
 	"net"
 	"reflect"
@@ -281,7 +282,7 @@ func TestAddrWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.writeErr {
 				t.Errorf("KaspaEncode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.writeErr)
@@ -301,7 +302,7 @@ func TestAddrWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.readErr {
 				t.Errorf("KaspaDecode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.readErr)

wire/msgblocklocator_test.go

@@ -2,6 +2,7 @@ package wire
 
 import (
 	"bytes"
+	"github.com/pkg/errors"
 	"io"
 	"reflect"
 	"testing"
@@ -232,7 +233,7 @@ func TestBlockLocatorWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.writeErr {
 				t.Errorf("KaspaEncode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.writeErr)
@@ -252,7 +253,7 @@ func TestBlockLocatorWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.readErr {
 				t.Errorf("KaspaDecode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.readErr)

wire/msgfeefilter_test.go

@@ -6,6 +6,7 @@ package wire
 
 import (
 	"bytes"
+	"github.com/pkg/errors"
 	"io"
 	"math/rand"
 	"reflect"
@@ -146,7 +147,7 @@ func TestFeeFilterWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.writeErr {
 				t.Errorf("KaspaEncode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.writeErr)
@@ -166,7 +167,7 @@ func TestFeeFilterWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.readErr {
 				t.Errorf("KaspaDecode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.readErr)

wire/msgfilteradd_test.go

@@ -6,6 +6,7 @@ package wire
 
 import (
 	"bytes"
+	"github.com/pkg/errors"
 	"io"
 	"reflect"
 	"testing"
@@ -126,7 +127,7 @@ func TestFilterAddWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.writeErr {
 				t.Errorf("KaspaEncode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.writeErr)
@@ -146,7 +147,7 @@ func TestFilterAddWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.readErr {
 				t.Errorf("KaspaDecode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.readErr)

wire/msgfilterload_test.go

@@ -6,6 +6,7 @@ package wire
 
 import (
 	"bytes"
+	"github.com/pkg/errors"
 	"io"
 	"reflect"
 	"testing"
@@ -172,7 +173,7 @@ func TestFilterLoadWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.writeErr {
 				t.Errorf("KaspaEncode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.writeErr)
@@ -192,7 +193,7 @@ func TestFilterLoadWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.readErr {
 				t.Errorf("KaspaDecode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.readErr)

wire/msggetblockinvs_test.go

@@ -6,6 +6,7 @@ package wire
 
 import (
 	"bytes"
+	"github.com/pkg/errors"
 	"io"
 	"reflect"
 	"testing"
@@ -207,7 +208,7 @@ func TestGetBlockInvsWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.writeErr {
 				t.Errorf("KaspaEncode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.writeErr)
@@ -227,7 +228,7 @@ func TestGetBlockInvsWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.readErr {
 				t.Errorf("KaspaDecode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.readErr)

wire/msggetblocklocator_test.go

@@ -2,6 +2,7 @@ package wire
 
 import (
 	"bytes"
+	"github.com/pkg/errors"
 	"io"
 	"reflect"
 	"testing"
@@ -190,7 +191,7 @@ func TestGetBlockLocatorWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.writeErr {
 				t.Errorf("KaspaEncode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.writeErr)
@@ -210,7 +211,7 @@ func TestGetBlockLocatorWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.readErr {
 				t.Errorf("KaspaDecode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.readErr)

wire/msggetdata_test.go

@@ -6,6 +6,7 @@ package wire
 
 import (
 	"bytes"
+	"github.com/pkg/errors"
 	"io"
 	"reflect"
 	"testing"
@@ -238,7 +239,7 @@ func TestGetDataWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.writeErr {
 				t.Errorf("KaspaEncode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.writeErr)
@@ -258,7 +259,7 @@ func TestGetDataWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.readErr {
 				t.Errorf("KaspaDecode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.readErr)

wire/msggetheaders_test.go

@@ -6,6 +6,7 @@ package wire
 
 import (
 	"bytes"
+	"github.com/pkg/errors"
 	"io"
 	"reflect"
 	"testing"
@@ -195,7 +196,7 @@ func TestGetHeadersWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.writeErr {
 				t.Errorf("KaspaEncode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.writeErr)
@@ -215,7 +216,7 @@ func TestGetHeadersWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.readErr {
 				t.Errorf("KaspaDecode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.readErr)

wire/msgheaders_test.go

@@ -6,6 +6,7 @@ package wire
 
 import (
 	"bytes"
+	"github.com/pkg/errors"
 	"io"
 	"reflect"
 	"testing"
@@ -296,7 +297,7 @@ func TestHeadersWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.writeErr {
 				t.Errorf("KaspaEncode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.writeErr)
@@ -316,7 +317,7 @@ func TestHeadersWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.readErr {
 				t.Errorf("KaspaDecode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.readErr)

wire/msginv_test.go

@@ -6,6 +6,7 @@ package wire
 
 import (
 	"bytes"
+	"github.com/pkg/errors"
 	"io"
 	"reflect"
 	"testing"
@@ -238,7 +239,7 @@ func TestInvWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.writeErr {
 				t.Errorf("KaspaEncode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.writeErr)
@@ -258,7 +259,7 @@ func TestInvWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.readErr {
 				t.Errorf("KaspaDecode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.readErr)

wire/msgmerkleblock_test.go

@@ -7,6 +7,7 @@ package wire
 import (
 	"bytes"
 	"crypto/rand"
+	"github.com/pkg/errors"
 	"io"
 	"reflect"
 	"testing"
@@ -237,7 +238,7 @@ func TestMerkleBlockWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.writeErr {
 				t.Errorf("KaspaEncode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.writeErr)
@@ -257,7 +258,7 @@ func TestMerkleBlockWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.readErr {
 				t.Errorf("KaspaDecode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.readErr)

wire/msgnotfound_test.go

@@ -6,6 +6,7 @@ package wire
 
 import (
 	"bytes"
+	"github.com/pkg/errors"
 	"io"
 	"reflect"
 	"testing"
@@ -228,7 +229,7 @@ func TestNotFoundWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.writeErr {
 				t.Errorf("KaspaEncode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.writeErr)
@@ -248,7 +249,7 @@ func TestNotFoundWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.readErr {
 				t.Errorf("KaspaDecode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.readErr)

wire/msgpong_test.go

@@ -6,6 +6,7 @@ package wire
 
 import (
 	"bytes"
+	"github.com/pkg/errors"
 	"io"
 	"reflect"
 	"testing"
@@ -169,7 +170,7 @@ func TestPongWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.writeErr {
 				t.Errorf("KaspaEncode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.writeErr)
@@ -189,7 +190,7 @@ func TestPongWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.readErr {
 				t.Errorf("KaspaDecode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.readErr)

wire/msgreject_test.go

@@ -6,6 +6,7 @@ package wire
 
 import (
 	"bytes"
+	"github.com/pkg/errors"
 	"io"
 	"reflect"
 	"testing"
@@ -265,7 +266,7 @@ func TestRejectWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.writeErr {
 				t.Errorf("KaspaEncode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.writeErr)
@@ -285,7 +286,7 @@ func TestRejectWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.readErr {
 				t.Errorf("KaspaDecode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.readErr)

wire/msgversion_test.go

@@ -6,6 +6,7 @@ package wire
 
 import (
 	"bytes"
+	"github.com/pkg/errors"
 	"io"
 	"net"
 	"reflect"
@@ -81,7 +82,7 @@ func TestVersion(t *testing.T) {
 	// accounting for ":", "/"
 	err = msg.AddUserAgent(strings.Repeat("t",
 		MaxUserAgentLen-len(customUserAgent)-2+1), "")
-	if _, ok := err.(*MessageError); !ok {
+	if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 		t.Errorf("AddUserAgent: expected error not received "+
 			"- got %v, want %T", err, MessageError{})
 
@@ -274,7 +275,7 @@ func TestVersionWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.writeErr {
 				t.Errorf("KaspaEncode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.writeErr)
@@ -294,7 +295,7 @@ func TestVersionWireErrors(t *testing.T) {
 
 		// For errors which are not of type MessageError, check them for
 		// equality.
-		if _, ok := err.(*MessageError); !ok {
+		if msgErr := &(MessageError{}); !errors.As(err, &msgErr) {
 			if err != test.readErr {
 				t.Errorf("KaspaDecode #%d wrong error got: %v, "+
 					"want: %v", i, err, test.readErr)